package com.system.comm.utils;

import java.math.BigInteger;
import java.util.Base64;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.spec.SecretKeySpec;

/**
 * AES加密[前端配合aes.js使用]
 * @author yuejing
 * @date 2020年5月20日
 */
public class FrameAesUtil {

	/** 密钥 (需要前端和后端保持一致) */
	private static final String KEY = "q2cd7tga9kd0mg1a";

	/** 算法 */
	private static final String ALGORITHMSTR = "AES/ECB/PKCS5Padding";

	/** 
	 * aes解密 
	 * @param encrypt 内容 
	 * @return 
	 * @throws Exception 
	 */
	public static String decrypt(String encrypt) {
		return decrypt(encrypt, KEY);
	}

	/** 
	 * aes加密 
	 * @param content 
	 * @return 
	 * @throws Exception 
	 */
	public static String encrypt(String content) {
		return encrypt(content, KEY);
	}

	/** 
	 * 将byte[]转为各种进制的字符串 
	 * @param bytes byte[] 
	 * @param radix 可以转换进制的范围，从Character.MIN_RADIX到Character.MAX_RADIX，超出范围后变为10进制 
	 * @return 转换后的字符串 
	 */
	public static String binary(byte[] bytes, int radix){
		// 这里的1代表正数
		return new BigInteger(1, bytes).toString(radix);
	}

	/** 
	 * base 64 encode 
	 * @param bytes 待编码的byte[] 
	 * @return 编码后的base 64 code 
	 */
	public static String base64Encode(byte[] bytes){
		return Base64.getEncoder().encodeToString(bytes);
	}

	/** 
	 * base 64 decode 
	 * @param base64Code 待解码的base 64 code 
	 * @return 解码后的byte[] 
	 * @throws Exception 
	 */
	public static byte[] base64Decode(String base64Code) throws Exception {
		return FrameStringUtil.isEmpty(base64Code) ? null : Base64.getDecoder().decode(base64Code);
	}


	/** 
	 * AES加密 
	 * @param content 待加密的内容 
	 * @param encryptKey 加密密钥 
	 * @return 加密后的byte[] 
	 * @throws Exception 
	 */
	public static byte[] aesEncryptToBytes(String content, String encryptKey) throws Exception {
		KeyGenerator kgen = KeyGenerator.getInstance("AES");
		kgen.init(128);
		Cipher cipher = Cipher.getInstance(ALGORITHMSTR);
		cipher.init(Cipher.ENCRYPT_MODE, new SecretKeySpec(encryptKey.getBytes(), "AES"));

		return cipher.doFinal(content.getBytes("utf-8"));
	}


	/** 
	 * AES加密为base 64 code 
	 * @param content 待加密的内容 
	 * @param encryptKey 加密密钥 
	 * @return 加密后的base 64 code 
	 * @throws Exception 
	 */
	public static String encrypt(String content, String encryptKey) {
		try {
			return base64Encode(aesEncryptToBytes(content, encryptKey));
		} catch (Exception e) {
			e.printStackTrace();
		}
		return null;
	}

	/** 
	 * AES解密 
	 * @param encryptBytes 待解密的byte[] 
	 * @param decryptKey 解密密钥 
	 * @return 解密后的String 
	 * @throws Exception 
	 */
	public static String aesDecryptByBytes(byte[] encryptBytes, String decryptKey) throws Exception {
		KeyGenerator kgen = KeyGenerator.getInstance("AES");
		kgen.init(128);

		Cipher cipher = Cipher.getInstance(ALGORITHMSTR);
		cipher.init(Cipher.DECRYPT_MODE, new SecretKeySpec(decryptKey.getBytes(), "AES"));
		byte[] decryptBytes = cipher.doFinal(encryptBytes);
		return new String(decryptBytes);
	}


	/** 
	 * 将base 64 code AES解密 
	 * @param encryptStr 待解密的base 64 code 
	 * @param decryptKey 解密密钥 
	 * @return 解密后的string 
	 * @throws Exception 
	 */
	public static String decrypt(String encryptStr, String decryptKey) {
		try {
			return FrameStringUtil.isEmpty(encryptStr) ? null : aesDecryptByBytes(base64Decode(encryptStr), decryptKey);
		} catch (Exception e) {
			e.printStackTrace();
		}
		return null;
	}

	/**
	 * 测试
	 */
	public static void main(String[] args) throws Exception {
		String content = "123";
		System.out.println("加密前：" + content);
		System.out.println("加密密钥和解密密钥：" + KEY);
		String encrypt = encrypt(content, KEY);
		System.out.println("加密后：" + encrypt);
		String decrypt = decrypt(encrypt, KEY);
		System.out.println("解密后：" + decrypt);
	} 
}